This invention relates to an antenna horn, and particularly such a horn that is of an injected molded plastic construction with the inner surface of an electromagnetic energy conductive material. The antenna horn of the present invention is particularly adapted for use with antennas of the Cassegrain type, and more particularly for a television receive only (TVRO) antenna.
Typically, TVRO antennas have been of the prime focus type. The highly sophisticated design techniques for Cassegrain antennas of a near field design have not heretofore been used in a TVRO antenna.
One of the problems associated with a Cassegrain antenna of a near field design is the cost. Such an antenna requires a sophisticated design to produce a compact Cassegrain antenna with high gain, high efficiency, low cross-polarization characteristics. Co-pending U.S. patent application entitled "Cassegrain Antenna for TVRO Application" filed concurrently herewith, the entirety of which is incorporated herein by reference, describes a TVRO Cassegrain antenna that achieves the aforementioned characteristics and does so at a relatively low cost. The present invention is directed to a horn that is particularly suited for the antenna of said co-pending application as its unique construction not only provides the desired electrical performance characteristics, but also is particularly suited to mass production techniques with low labor and material costs. While the horn of the present invention is particularly adapted for use with the antenna of said co-pending application, it is to be understood that many of the features of the horn are also suited for other horn designs and for use with other types of antennas.
Generally, the horn of the present invention is of a plastic molded construction with the inner surface of the horn being of an electromagnetic energy conductive material. More particularly, the horn is comprised of identical sections, each section being of molded plastic construction with the sections then joined such as by solvent welding to form the horn. The inner surface of the horn is plated, such as first with a coating of copper and then nickel, to provide the electromagnetic energy conductive surface. An outer weather-protective coating may also be applied.
In a particular adaptation of these features of the invention, the horn may be a corrugated, profiled horn which is circularly symmetric. Moreover, the horn may also include integrally molded plastic reinforcing and securing means for securing the horn to a mounting structure of the antenna with which it is to be used.
These and other features and advantages of the invention are apparent from the description to follow.